Pretty One
by FallenQueen2
Summary: Curiosity was always a weakness of Magnus'. Curiosity for what humans would do if they caught him and curiosity for this pretty new human. Shadowhunter Bingo!
1. Chapter 1: Mermaid AU

**For the rest of their lives**

**Square Filled: Arranged Marriage **

**Ship: Jace Wayland/Alec Lightwood**

**Rating: G**

**Tags: Shadowhunterbingo, arranged marriage, Alpha/Beta/Omega, Alpha Jace, Omega Alec, protective Jace**

**Summary: Valentine forced Jace into an arranged marriage to his childhood friend and Omega Alec. This turns out to b the best thing that has ever happened to Jace. **

**Created for shadowhunterbingo**

Jace sat on the edge of the bed in his bedroom, silently lacing up his combat boots before straightening up and peering over his shoulder. Jace fought back a smile at the sight of the Omega who was sprawled on the other side of his bed. Alec was breathing softly, his face buried in one of his pillows and his dark hair messed up while the gold sheets were tangled around his waist and bare legs.

Jace resisted the urge to shed his clothes and crawl back into the bed with the sweet-smelling Omega. Alec sighed as he twisted around until he was flat on his back, one arm flung over his head allowing Jace to see the marriage rune standing out against Alec's pale skin.

Jace traced the matching rune on his wrist and shook himself silently before rising from the bed. Jace strapped his blades to his body and walked around the mattress to Alec's side of the bed. Jace brushed Alec's messy bang off of his husband's forehead before stepping out of the room. Jace shut the door behind himself and set a scowl on his face when he saw Jonathan lounging against the front door with a knowing smirk on his face.

"You took your precious time, is your Omega whore keeping you busy?" Jonathan snarked and Jace fought against shoving his blade into the other blond.

"I did what Valentine wanted and married the Lightwood, what else does he want from me?" Jace snarled unable to stop himself, he had followed his so-called 'father's' every order and that included marrying one the Omega son of one of his right hands. That Jace didn't mind, Alec was beautiful, strong, fierce, sassy and smelt amazing to Jace.

"Careful bother dear, I can always ask father to give your Omega whore to me instead, maybe I can put a pup in his stomach as you seem to be failing at that part of your mission," Jonathan commented before stilling when a small dagger embedded itself in the wood of the doorframe next to him and met Jace's glowing red Alpha eyes as the other blond lowered his arm.

"Do not even try it and do not call Alec a whore. He's ten times the warrior than you ever will be." Jace snarled, his protective instincts flaring up high.

"Alright, alright, understood." Jonathan now understood why Valentine had pushed Jace towards the eldest Lightwood.

"Tell Valentine that I'm not coming in today, I'm spending it with my husband." Jace decided as he bared his teeth at the other blond who held up his hands.

"Done," Jonathan agreed and slipped out of the apartment. He smiled to himself; he hoped to see a pregnant Omega wandering about soon.

"Jace?" Alec's sleepy voice rung out as the tall Omega stepped out of the bedroom; a dagger clutched in his right hand and held up high. Jace preened at seeing his husband almost fully naked but already armed and ready to fight.

"It's fine Alec, just telling Jonathan off. I'm not going in today, Valentine can shove it." Jace unstrapped his blades and shrugged off his jacket as Alec lowered the dagger with a look of disbelief.

"Are you sure? I don't want you to get in trouble with Valentine because of me…" Alec worried his lower lip; he knew how violent Valentine could get and how much Jace had borne the brunt of it.

"Are you worried about me?" Jace's eyes widened, he and Alec had trained together since they were kids, but when Alec presented as an Omega his parents took him away and Jace hadn't seen the tall Omega until his wedding day. The day that the two of them were bound together for life as a mated pair, the day Jace thought was going to be his hell was to begin until Alec walked down that aisle.

"Of course I'm worried about you idiot! Stupid Alpha." Alec muttered as he set his dagger down and ambled into the kitchen to start making coffee.

"You liiikkkeee me," Jace teased as a genuine smile appeared on his lips as he followed the Omega.

"I've always liked you dumbass, angel knows why though," Alec muttered, refusing to look at the blond as he messed with the coffee machine.

"Really?" Jace came closer, his heart pounding in his chest as his hope rose.

"Do you think me presenting as an Omega was the only reason I was pulled away from you when we were teens? I wasn't as mindful of my feelings as I should have been," Alec just sound sad now and every part of Jace rebelled against that. He had silently sworn to himself when he drew the rune on Alec's wrist that he would do anything to keep Alec happy.

"I was so blind," Jace whispered before he curled his arms around Alec, plastering his front of Alec's back and inhaled Alec's soft scent deeply, allowing it to calm him down.

"I was stubborn," Alec sagged back against Jace and closed his eyes as the coffee began to brew.

"This is the only thing I will ever be grateful to Valentine for," Jace admitted and allowed Alec to turn in his arms so they could look at each other properly.

"You're grateful you got forced into marrying me?" Alec's eyebrows furrowed together and Jace didn't resist the urge to kiss the little wrinkle between them. Alec gasped and his cheeks turned red as his mouth opened and shut like a fish.

"Very grateful," Jace said honestly as he cupped Alec's cheek carefully.

"Are you sure?" Alec whispered as he leaned into the Alpha's palm unable to help himself.

"Extremely, when I drew that rune on you I made a promise to myself that I would do anything to keep you happy because you make me happy, you always have and those years without you were hell for me." Jace wasn't usually one who was so honest about his feelings but for Alec, he would be.

"I did the same," Alec admitted as he dropped his head down and rested his forehead against Jace's and the blond let out a soft sigh.

"We're just a couple of idiots huh?" Jace whispered sounding fond.

"We'll be each other's idiots for the rest of our lives then," Alec said and Jace couldn't hide the pleased smile at the words and he inhaled Alec's scent again, this time he was able to tell that Alec was just as happy as he was.

"For the rest of our lives," Jace agreed and tipped his head up to kiss Alec properly, their first kiss since their wedding and Jace was looking forward to being able to kiss Alec like this for the rest of their lives.


	2. Chapter 2: Soulbond

**Pretty One**

**Ao3 Link**

**Square Filled: soulbond **

**Ship: Magnus Bane/Alec Lightwood**

**Rating: G**

**Tags: Shadowhunterbingo, mermaid AU, soulbond Demonic Merman Magnus Bane, powerful Magnus Bane, Shadowhunter Alec Lightwood, Prince of Edom Magnus Bane**

**Summary: Curiosity was always a weakness of Magnus'. Curiosity for what humans would do if they caught him and curiosity for this pretty new human. **

**Created for shadowhunterbingo**

**Chapter 2 **

Alec slowly rubbed a towel against his hair, unable to stop from staring into the mirror in his bathroom back in the Institute. His once unmarked chest was now marked with a golden handprint, a wedded handprint that belonged to the demonic merman he had met a few days ago.

Alec had left his encounter with the merman out of his report when he finally had made it back to the Institute that night; he had left a lot out if he was being honest. This was something personal and he didn't want anyone knowing what this mark meant until Alec sorted out what it meant to him.

Oh, he knew all about soul marks and soul bonds, he had seen Jace's appear when he met Clary and that alone had felt like a sword in the chest but he was happy for his Parabatai. He was even happy his little sister had found her' in Clary's mundane-turned vampire friend Simon. Alec had seen soul bonds form and he had seen them shatter when one half died and he had seen people together whose souls were not meant for each other.

He saw the love and the pain of soul bonds in equal. He had been unsure he ever wanted one once Jace got his from Clary, but now that his soul bond with that beautiful merman was staring him in his face Alec couldn't deny he had truly wanted this. He had wanted someone who was meant for him, to be the other half of his soul.

What was making Alec question everything was the fact his soul mate was very obviously a demon from Edom, a powerful one at that from the display of power he had shown to save them both that day in the tank. Alec set the towel down and traced the outline of the golden handprint, he had never seen or heard of a golden soul mark, but he also had never heard of a Shadowhunter being bonded to a demon.

Alec pulled on a shirt, glad the mark was low enough on his chest to be hidden by most of his shirts and now he just had to make sure he didn't take his shirt off during training sessions and no one should be the wiser to the fact he had gotten his soul mark.

Alec double-checked his weapons before leaving his room, heading toward the ops centre to make sure the on-going missions were proceeding smoothly.

"Status report!" Alec called out when he noticed the alarms blaring and he quickened his stride to a run. He skidded to a stop by Izzy and Jace who were staring at a video feed on the screens.

"A portal from Edom opened up in that warehouse you cleared of Circle members a few days ago… Nothing has come out yet, it's just sitting open like it's waiting for something." Jace said in confusion as Izzy checked some stats.

"It's stable and isn't flaring out with demonic energy that usually summons the lower levels to it. Wait, it's power levels are fluxing, I think something is coming through!" Izzy corrected herself and all their eyes were drawn back to the video feed and Alec felt his breath catch in his chest as his soul mark burned but it was a pleasant warmth.

His soul mate, the demonic merman's upper half was poking out of the portal. His golden cat eyes were looking around and an actual pout appeared on his lips when he didn't see what or who he was looking for. They watched as Alec's soulmate's head ducked back and the portal fizzled before fading from sight.

"Demonic levels are returning to normal levels," Izzy said quietly as the alarms were cut now that the threat was passed.

"That was weird right?" Jace questioned as his eyebrows furrowed together.

"Very, that must have been one of the higher classes of demons. It seemed to be looking for something and seemed sad when it didn't see what it was looking for." Izzy hummed as she picked up a tablet to go over a report.

"Call me if the portal reappears," Alec managed to get out before he was turning on his heels and heading back to his room. Alec closed the door to his room before leaning against it, his hand splayed across his soul mark as he inhaled deeply. Alec wanted to go back to that warehouse, to see if his soul mate would reappear. Alec wanted to know his soulmate's name, he wanted to know everything about the merman, he wanted so much but he knew he couldn't.

There was no way he could find his soulmate and vice versa, how would a Shadowhunter and high-class demonic merman ever be able to be together? Can soul bonds even be created for demons? Alec hung his head and stroked his soul mark over his shirt, sadness seeping into his very bones at the thoughts that spiralled inside of his head.

Alec gasped when he felt his soul mark burn pleasantly again and his head jerked up when paper began to blow in his room. Alec watched wide-eyed and leaned against the door of his room as a familiar portal began to spin into creation. Alec knew he should be triggering an alarm, reaching for a weapon; anything but instead he just watched and waited until his soul mate stuck his head out of the portal again.

This time a happy smile crossed his soul mate's lips and his golden cat eyes shone brightly.

"I found you pretty one, my pretty soul bond." The demon crooned happily as he held up his clawed right hand to show a matching gold print spanning the length of the limb. Something inside of Alec relaxed and he found himself taking a step forward, reaching out towards his soul mate.

"I will protect you pretty one, nothing will harm you while you are at my side." Alec's soul mate crooned, his voice washing over Alec in a wave of warmth and something clicked inside of Alec when their hands tangled together.

"Do you promise?" Alec found himself asking as the fires of Edom licked at his skin, but surprisingly leaving him un-burnt.

"I promise pretty one," The merman promised and Alec closed his eyes in contentment as he was pulled fully into the portal, which winked out of existence mere moments before the door was flung open and Jace and Izzy lunged into the room with their weapons at the ready but already too late.


	3. Chapter 3: Outside POV

**Pretty One**

**Ao3 Link**

**Square Filled: Outside POV **

**Ship: Magnus Bane/Alec Lightwood**

**Rating: G**

**Tags: Shadowhunterbingo, mermaid AU, soulbond, outside POV, Demonic Merman Magnus Bane, powerful Magnus Bane, Shadowhunter Alec Lightwood, Prince of Edom **

**Magnus Bane**

**Summary: Curiosity was always a weakness of Magnus'. Curiosity for what humans would do if they caught him and curiosity for this pretty new human. **

**Created for shadowhunterbingo**

**Chapter 3**

Asmodeus dragged his fingertips through the bloodied water as he lounged on his throne made of dark coloured corals. Asmodeus watched passively as his guards cleared away the demon that had dared to question his son's motives. Asmodeus had to admit that the demon had a point, but to speak so boldly against Magnus was an intolerable offence.

Asmodeus pushed up out of his chair and floated over to the window of his throne room and stared down at the courtyard where his son was with the human he brought from the surface world. Edom was separated into many different parts; Asmodeus had utter and complete control over the aquatic part as he and his descendants were mer-people for a lack of a better term. Asmodeus had tolerated many of his son's whims over the centuries, he had to admit that this whim was interesting if not frustrating as he stared down at the human, the Shadowhunter of all things that were peacefully resting on the ground next to Magnus. The Prince had his tail carefully wrapped around Alec's body in a possessive, protective way and Alexander was sleeping peacefully inside of that protective circle.

Magnus had asked him to create a spell so this human could not only survive in Edom but also more importantly survive in Asmodeus' underwater kingdom. Asmodeus had been an inch away from telling Magnus that the human could drown and die for all he cared.

Asmodeus touched his bare hip with one hand, feeling the faint scars of his own now faded soul mark. His heart had about stopped when Magnus had shoved his gold marked hand in his face, showing his father that he had found his one, his soul bonded and that was why he was asking for the spell.

Asmodeus gave his son the spell in a heartbeat, he knew both love and pain from soul mates but he also knew that if he denied his son this then Magnus would do something drastic and dramatic to ensure he was with his soul mate. Asmodeus rubbed at his hip again as he watched as the human, Alexander, eyes scrunched up when Magnus dropped a kiss on his nose in a loving way Asmodeus had not seen in many centuries from his son.

Asmodeus watched as Alexander woke up fully and twisted in Magnus' arms so he could straddle the Prince and smiled angelically down at him with his non-webbed hands cupping Magnus' face, bringing it up for a kiss. Asmodeus watched as Magnus wrapped his arms around his soul mate and his tail swayed in happiness as the two bonded embraced in an embrace so full of love that Asmodeus had to look away.

Asmodeus settled back in his throne and waved away the bits of blood that were remaining from the demon previously. He would do anything for his son and his bonded one; he would protect their love if it was in his power and if that meant slaughtering every demon that dared to speak against them then so be it.

**Chapter 4 is NSFW for please go to my Ao3 **

/works/22603342/chapters/54290878


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